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[UPDATE: Unfortunately I’ve confused the 1979 JASON report with the Charney report that followed it (and referred to it) later that year. My bad! The Charney report is available online and is summarized in item 2 below; I could not find a copy of the JASON report online, but report some available info on it in item 1]

1. The 1979 JASON report: “The Long Term Impact of Atmospheric Carbon Dioxide on Climate”

“Description/Abstract If the current growth rate in the use of fossil fuels continues at 4.3% per year, then the CO/sub 2/ concentration in the atmosphere can be expected to double by about 2035 provided the current partition of CO/sub 2/ between the atmosphere, biosphere, and oceans is maintained as is the current mix of fuels. Slower rates of anticipated growth of energy use lead to a doubling of the carbon content of the atmosphere sometime in the period 2040 to 2060.

“This report addresses the questions of the sources of atmospheric CO/sub 2/; considers distribution of the present CO/sub 2/ among the atmospheric, oceanic, and biospheric reservoir; and assesses the impact on climate as reflected by the average ground temperature at each latitude of significant increases in atmospheric CO/sub 2/. An analytic model of the atmosphere was constructed (JASON Climate Model). Calculation with this zonally averaged model shows an increase of average surface temperature of 2.4/sup 0/ for a doubling of CO/sub 2/. The equatorial temperature increases by 0.7/sup 0/K, while the poles warm up by 10 to 12/sup 0/K. The warming of climate will not necessarily lead to improved living conditions everywhere. Changes in sea level, in agricultural productivity, and in water availability can be anticipated, but the dimensions of their economic, political, or social consequences can not.”

“Description/Abstract The questions of the sources of atmospheric carbon dioxide are addressed; distribution of the present carbon dioxide among the atmospheric, oceanic, and biospheric reservoirs is considered; and the impact on climate as reflected by the average ground temperature at each latitude of significant increases in atmospheric carbon dioxide is assessed.

“A new model for the mixing of carbon dioxide in the oceans is proposed. The proposed model explicitly takes into account the flow of colder and/or saltier water to great depths. We have constructed two models for the case of radiative equilibrium treating the atmosphere as gray and dividing the infrared emission region into nine bands. The gray atmosphere model predicts an increase of average surface temperature of 2.8/sup 0/K for a doubling of CO/sub 2/, a result about a degree less than the nine band model. An analytic model of the atmosphere was constructed (JASON Climate Model). Calculation with this zonally averaged model shows an increase of average surface temperature of 2.4/sup 0/ for a doubling of CO/sub 2/. The equatorial temperature increases by 0.7/sup 0/K while the poles warm up by 10 to 12/sup 0/K. The JASON climate model suffers from a number of fundamental weaknesses. The role of clouds in determining the albedo is not adequately taken into account nor are the asymmetries between the northern and southern hemisphere.(JGB)”

Naomi Oreskes and Jonathan Renouf describe the 1979 JASON report as follows in The Sunday Times:

“In 1979 they produced their report: coded JSR-78-07 and entitled The Long Term Impact of Atmospheric Carbon Dioxide on Climate. Now, with the benefit of hind-sight, it is remarkable how prescient it was.

“Right on the first page, the Jasons predicted that carbon dioxide levels in the atmosphere would double from their preindustrial levels by about 2035. Today it’s expected this will happen by about 2050. They suggested that this doubling of carbon dioxide would lead to an average warming across the planet of 2-3C. Again, that’s smack in the middle of today’s predictions. They warned that polar regions would warm by much more than the average, perhaps by as much as 10C or 12C. That prediction is already coming true – last year the Arctic sea ice melted to a new record low. This year may well set another record.

“Nor were the Jasons frightened of drawing the obvious conclusions for civilisation: the cause for concern was clear when one noted “the fragility of the world’s crop-producing capacity, particularly in those marginal areas where small alterations in temperature and precipitation can bring about major changes in total productivity”.

2. Here is basic information on the Charney Report, which Orsekes and Renouf also mention

Report of an Ad Hoc Study Group on Carbon Dioxide and Climate, Woods Hole, Massachusetts, July 23-27, 1979, to the Climate Research Board, Assembly of Mathematical and Physical Sciences, National Research Council

ISBN: 978-0-309-11910-8,34 pages, 6 x 9, paperback (1979)

“NOTICE: The project that is the subject of this report was approved by the Governing Board of the National Research Council, whose members are drawn from the Councils of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine. The members of the Committee responsible for the report were chosen for their special competencies and with regard for appropriate balance.

This report has been reviewed by a group other than the authors according to pro­cedures approved by a Report Review Committee consisting of members of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine.”

Ad Hoc Study Group on Carbon Dioxide and Climate

Jule G. Charney, Massachusetts Institute of Technology, Chairman

Akio Arakawa, University of California, Los Angeles

D. James Baker, University of Washington

Bert Bolin, University of Stockholm

Robert E. Dickinson, National Center for Atmospheric Research Richard M. Goody, Harvard University

Douglas H. Sargeant, National Oceanic and Atmospheric Administration David Slade, Department of Energy

Herbert L. Wiser, Environmental Protection Agency

STAFF

John S. Perry, National Research Council, Executive Secretary

Robert S. Chen, National Academy of Sciences, Resident Fellow

Summary and Conclusions

“We have examined the principal attempts to simulate the effects of increased atmospheric CO2 on climate. In doing so, we have limited our considerations to the direct climatic effects of steadily rising atmospheric concentrations of CO2 and have assumed a rate of CO2 increase that would lead to a doubling of airborne concentrations by some time in the first half of the twenty-first century. As indicated in Chapter 2 of this report, such a rate is consistent with observations of CO2 increases in the recent past and with projections of its future sources and sinks. However, we have not examined anew the many uncertainties in these projections, such as their implicit assumptions with regard to the workings of the world economy and the role of the biosphere in the carbon cycle. These impose an uncertainty beyond that arising from our necessarily imperfect knowledge of the manifold and complex climatic system of the earth.

“When it is assumed that the CO2 content of the atmosphere is doubled and statistical thermal equilibrium is achieved, the more realistic of the modeling efforts predict a global surface warming of between 2°C and 3°C, with greater increases at high latitudes. This range reflects both uncertainties in physical understanding and inaccuracies arising from the need to reduce the mathematical problem to one that can be handled by even the fastest avail­able electronic computers. It is significant, however, that none of the model calculations predicts negligible warming.

“The primary effect of an increase of CO2 is to cause more absorption of thermal radiation from the earth’s surface and thus to increase the air tem­perature in the troposphere. A strong positive feedback mechanism is the accompanying increase of moisture, which is an even more powerful absorber of terrestrial radiation. We have examined with care all known negative feed­back mechanisms, such as increase in low or middle cloud amount, and have concluded that the oversimplifications and inaccuracies in the models are not likely to have vitiated the principal conclusion that there will be appreciable warming. The known negative feedback mechanisms can reduce the warming, but they do not appear to be so strong as the positive moisture feedback. We estimate the most probable global warming for a doubling of CO2 to be near 3°C with a probable error of :i: 1.5°C. Our estimate is based primarily on our review of a series of calculations with three-dimensional models of the global atmospheric circulation, which is summarized in Chapter 4. We have also reviewed simpler models that appear to contain the main physical factors. These give qualitatively similar results.

“One of the major uncertainties has to do with the transfer of the increased heat into the oceans. It is well known that the oceans are a thermal regulator, warming the air in winter and cooling it in summer. The standard assumption has been that, while heat is transferred rapidly into a relatively thin, well-mixed surface layer of the ocean (averaging about 70 m in depth), the trans­fer into the deeper waters is so slow that the atmospheric temperature reaches effective equilibrium with the mixed layer in a decade or so. .It seems to us quite possible that the capacity of the deeper oceans to absorb heat has been seriously underestimated, especially that of the intermediate waters of the subtropical gyres lying below the mixed layer and above the main thermocline. If this is so, warming will proceed at a slower rate until these inter­mediate waters are brought to a temperature at which they can no longer absorb heat.

“Our estimates of the rates of vertical exchange of mass between the mixed and intermediate layers and the volumes of water involved give a delay of the order of decades in the time at which thermal equilibrium will be reached. This delay implies that the actual warming at any given time will be appreciably less than that calculated on the assumption that thermal equilibrium is reached quickly. One consequence may be that perceptible temperature changes may not become apparent nearly so soon as has been anticipated. We may not be given a warning until the CO2 loading is such that an appreciable climate change is inevitable. The equilibrium warming will eventually occur; it will merely have been postponed.

“The warming will be accompanied by shifts in the geographical distributions of the various climatic elements such as temperature, rainfall, evaporation, and soil moisture. The evidence is that the variations in these anomalies with latitude, longitude, and season will be at least as great as the globally averaged changes themselves, and it would be misleading to predict regional climatic changes on the basis of global or zonal averages alone. Unfortunately, only gross globally. and zonally averaged features of the present climate can now be reasonably well simulated. At present, we cannot simulate accurately the details of regional climate and thus cannot predict the locations and intensities of regional climate changes with confidence. This situation may be expected to improve gradually as greater scientific understanding is acquired and faster computers are built.

“To summarize, we have tried but have been unable to find any overlooked or underestimated physical effects that could reduce the currently estimated global warmings due to a doubling of atmospheric CO2 to negligible propor­tions or reverse them altogether. However, we believe it quite possible that the capacity of the intermediate waters of the oceans to absorb heat could delay the estimated warming by several decades. It appears that the warming will eventually occur, and the associated regional climatic changes so important to the assessment of socioeconomic consequences may well be significant, but unfortunately the latter cannot yet be adequately projected.”